This invention relates generally to a system and method for positioning an organ, and more particularly to a system capable of positioning, manipulating, stabilizing and/or holding a heart during cardiac surgery. This invention also relates to a positioning system and method that includes monitoring one or more chemical, physical or physiological characteristics of a bodily tissue or fluid during a medical procedure.
This invention relates generally to a device and method for positioning an organ, such as the heart, and more particularly to a suction device for grasping, orienting and/or positioning an organ, such as the heart during cardiac surgery.
Coronary artery disease remains the leading cause of morbidity and mortality in Western societies. Coronary artery disease is manifested in a number of ways. For example, disease of the coronary arteries can lead to insufficient blood flow to various areas of the heart. This can lead to the discomfort of angina and the risk of ischemia. In severe cases, acute blockage of coronary blood flow can result in irreversible damage to the myocardial tissue including myocardial infarction and the risk of death.
A number of approaches have been developed for treating coronary artery disease. In less severe cases, it is often sufficient to merely treat the symptoms, with pharmaceuticals, or treat the underlying causes of the disease, with lifestyle modification. In more severe cases, the coronary blockage can be treated endovascularly or percutaneously using techniques such as balloon angioplasty, atherectomy, laser ablation, stents, and the like.
In cases where these approaches have failed or are likely to fail, it is often necessary to perform a coronary artery bypass graft procedure. This procedure generally consists of the following steps: First, direct access to the heart is achieved. This is usually done by opening the chest by median sternotomy and spreading the left and right rib cage apart; and opening the pericardial sac to achieve direct access to the heart.
Next, a blood vessel or vessels for use in the graft procedure are mobilized from the patient. This usually entails mobilizing either a mammary artery or a saphenous vein, although other graft vessels may also be used.
Next, a heart-lung or cardiopulmonary bypass is performed. This usually entails arterial and venous cannulation, connecting the bloodstream to a heart-lung machine, cooling the body to about 32 degrees Celsius, cross-clamping of the aorta and cardioplegic perfusion of the coronary arteries to arrest and cool the heart to about 4 degrees Celsius. The arrest or stoppage of the heart is generally required because the constant pumping motion of the beating heart would make surgery upon the heart difficult in some locations and extremely difficult if not impossible in other locations
Once cardiac arrest is achieved, then a graft (or grafts) is attached to the relevant portions of a coronary artery (or arteries) followed by weaning from the cardiopulmonary bypass, restarting the heart and decannulation. Finally the chest is closed.
One area which may create difficulties for the patient and extra expense and time for the procedure involves the cardiopulmonary bypass. In a cardiopulmonary bypass all the patient""s blood, which normally returns to the right atrium, is diverted to a system which supplies oxygen to the blood and removes carbon dioxide and returns the blood, at sufficient pressure, into the patient""s aorta for further distribution into the body. Generally such a system requires several separate components, including an oxygenator, several pumps, a reservoir, a blood temperature control system, filters as well as flow, pressure and temperature sensors.
Problems may develop during cardiopulmonary bypass due to the reaction blood has to non-endothelially lined surfaces, i.e. surfaces unlike those of a blood vessel. In particular, exposure of blood to foreign surfaces results in the activation of virtually all the humoral and cellular components of the inflammatory response, as well as some of the slower reacting specific immune responses. Other complications from cardiopulmonary bypass include loss of red blood cells and platelets due to shear stress damage. In addition, cardiopulmonary bypass requires the use of an anticoagulant, such as heparin. This may, in turn, increase the risk of hemorrhage. Finally cardiopulmonary bypass sometimes necessitates giving additional blood to the patient. The additional blood, if from a source other than the patient, may expose the patient to blood born diseases.
Due to the risks incurred during cardiopulmonary bypass, others have attempted to perform a coronary artery bypass graft procedure without cardiac arrest and cardiopulmonary bypass. For example, Trapp and Bisarya in xe2x80x9cPlacement of Coronary Artery Bypass Graft Without Pump Oxygenatorxe2x80x9d, Annals Thorac. Surg. Vol. 19, No. 1, (January 1975) pgs. 1-9, immobilized the area of the bypass graft by encircling sutures deep enough to incorporate enough muscle to suspend an area of the heart and prevent damage to the coronary artery. More recently Fanning et al. in xe2x80x9cReoperative Coronary Artery Bypass Grafting Without Cardiopulmonary Bypassxe2x80x9d, Annals Thorac. Surg. Vol. 55, (February 1993) pgs. 486-489 also reported immobilizing the area of the bypass graft with stabilization sutures.
Suction stabilization systems, such as the Medtronic OCTOPUS(copyright) Tissue Stabilizer and Accessories (available from Medtronic, Inc., Minneapolis, Minn. USA), the current model being designated the xe2x80x9cOCTOPUS 3(trademark) stabilization systemxe2x80x9d, use suction to grip and immobilize the surface of the heart. Additionally, the system allows the surgeon to manipulate the anastomosis site into better view by rotating and supporting the heart. See, also, e.g., U.S. Pat. Nos. 5,836,311; 5,927,284 and 6,015,378, and co-assigned U.S. patent application Ser. No. 09/396,047, filed Sep. 15, 1999, Ser. No. 09/559,785, filed Apr. 27, 2000, and Ser. No. 09/678,203, filed Oct. 2, 2000; and European Patent Publication No. EP 0 993 806. The OCTOPUS(trademark) stabilizer facilitates moving or repositioning the heart to achieve better access to areas which would otherwise be difficult to access, such as the posterior or backside of the heart.
This invention provides an organ positioning device and method that employs suction to hold organ tissue to the device. The device allows the organ, for example, heart to be positioned in a desired orientation but otherwise allowing movement of the heart as the heart beats. The device is designed to be relatively atraumatic to heart tissue.
Generally, a heart positioning device of the present invention comprises a resiliently-flexible suction pad or head having a plurality of legs that flex to conform to the surface of the heart. The suction pad has vacuum passageways in fluid communication with the legs to apply suction between the legs and the surface of the heart. A vacuum line is connected to the vacuum passageway. A support arm is connected to the suction pad to position the suction pad to thereby position or hold the heart.
The suction pad preferably is generally starfish-shaped in addition to being resiliently flexible so that the legs flex to conform and/or collapse partly or completely to the surface of the heart, and can be attached with suction to the heart at the apex of the heart or elsewhere along the heart. The starfish shape also allows the suction pad to be oriented relative to the anatomy of the heart, for example, to improve access to an artery.
A second aspect of the invention is the method of use of the device to position or orient the heart during cardiac surgery, such as but not limited to open-chest, beating-heart surgery.
In a third aspect of the invention, a heart positioning device generally comprises a suction head having a vacuum passageway for applying suction between the suction head and the surface of the heart, a vacuum line connected to the vacuum passageway, a support arm connected to the suction head to position the suction head to thereby position or hold the heart, and a bellows-type suspension element connecting the suction head and support arm. The bellows-type suspension element flexes to allow the suction head to move in response to beating of the heart.
A fourth aspect of the invention is a suction head for use in a heart positioning device. The suction head is formed of resiliently flexible material. The suction head has at least one vacuum passageway for applying suction to the surface of the heart, and a resiliently flexible peripheral flange. The suction head and/or flange is sufficiently resiliently flexible that the suction head draws down toward the surface of the heart more than the surface of the heart is pulled into the suction head.
A fifth aspect of the invention is a suction head having a porous material such as a porous membrane, screen, mesh, open cell foam, fabric or the like intermediate between the tissue and vacuum orifice to prevent the vacuum orifice and tissue from being drawn together and closing the orifice. This is particularly important for fatty tissues on the heart that may be pulled into the suction head and block the fluid communication between the vacuum passageway and the vacuum channels. During operation of the device, the porous material may engage tissue and may be provided with a textured surface to improve frictional contact with the tissue.
The device may be used, for example, in combination with a heart stabilizer, such as the stabilization system sold under the trade designation xe2x80x9cOCTOPUS 3xe2x80x9d(trademark) by Medtronic, Inc., Fridley, Minn., USA. See, also, e.g., U.S. Pat. Nos. 5,836,311; 5,927,284 and 6,015,378, and co-assigned U.S. patent application Ser. No. 09/396,047, filed Sep. 15, 1999, Ser. No. 09/559,785, filed Apr. 27, 2000, and Ser. No. 09/678,203, filed Oct. 2, 2000.